I also was advised minimum of 3ft and I chose a 4ft (1225mm) glass enclosure figuring that if our BTS grows to expected around 60cm it will be half the length of the enclosure! Also found the temp gradient good with this size. I keep the lights in individual lamps sitting on the mesh top.
I found though that having the little Bub in the big enclosure he seemed a bit too scared. Hid all the time. So I filled it with lots of low lying things for him to explore his cage under cover (ie without being too exposed) using (artificial) logs, plants, and skulls and holey cardboard boxes and toilet paper/ paper towel rolls. He went exploring much more comfortably after that. I have a small concrete paver in there for basking but he doesnt bask.
I don't have any other pets BUT I did keep a lock on the enclosure to keep out the little kid. Funnily enough he seemed much more interested in the lock itself and attracted lots of attention, so much for that theory.

I have the lock off now and he only looks in sometimes and knows he's not supposed to touch without us there.
Keeping the enclosure looking pretty with plants and interesting things keeps hubby happy, along with the fact that there is nothing in there to be allergic too and he doesn't have to do anything for the pet!
I'd also be interested to read people's thoughts on glass vs melamine. I like glass because it's so easy to clean with bleach etc (especially when I had to treat for mites) and it looks nice too, but melamine probably provides a bit more 'privacy' for BTS, helps keep the temps up, and is stackable.